6,407 research outputs found
Input and system identification of the Hualien soil-structure interaction system using earthquake response data
No full textThis paper presents an input and system identification technique for a soil-structure interaction system using earthquake response data. Identification is carried out on the Hualien large-scale seismic test structure, which was built in Taiwan for international joint research. The identified quantities are the input ground acceleration as well as the shear wave velocities of the near-field soil regions and Young's moduli of the shell sections of the structure. The earthquake response analysis on the soil-structure interaction system is carried out using the finite element method incorporating the infinite element formulation for the unbounded layered soil medium and the substructured wave input technique. The criterion function for the parameter estimation is constructed using the frequency response amplitude ratios of the earthquake responses measured at several points of the structure, so that the information on the input motion may be excluded. The constrained steepest descent method is employed to obtain the revised parameters. The simulated earthquake responses using the identified parameters and input ground motion show excellent agreement with the measured responses. Copyright 0 2003 John Wiley Sons, Ltd
Experimental investigation on smoke propagation in a transversely ventilated tunnel
No full textIn order to determine the key features of the fire safety design in transversely ventilated tunnels, the smoke propagation characteristics are examined as a function of fire size, fire location, and airflow rates of supply and exhaust. A 12-m long scale model of the Memorial tunnel, with a scale down ratio of cross section 1/20, is used. Fire sizes and ventilation rates in real tunnels are then deduced from the Froude similarity. In general, it is found that the smoke propagating distance increases with the fire size and decreases with the exhaust ventilation rate. When the fire location is off-centered, the propagating distance becomes substantially larger than that of the centered fire with the same size. A hazardous situation generated from an imbalance between the supply rate and the exhaust rate is also observed. The results suggest that the smoke propagating distance and/or the smoke filling may serve as good criteria for determining the transverse ventilation rate
Novel Manufacturing Method of GI Copolymer Optical Fiber Preform and Its Optical Characteristics
No full textNear-time-optimal trajectory planning for wheeled mobile robots with translational and rotational sections
No full textWe derive a near-time-optimal trajectory for wheeled mobile robots (WMRs) satisfying the following: 1) initial and final postures/velocities as well as 2) battery voltage and armature current constraints, under assumptions of simplified dynamics and constant translational/rotational velocity sections. We use a simplified dynamic model for WMRs neglecting inductances of motor armatures and divide our trajectory generation algorithm for cornering motion into three sections, We specify a path-deviation requirement for obstacle avoidance. Transforming dynamics into uncorrelated form with regard to translational and rotational velocities, we make extreme control possible. By splining rotational section with translational sections and determining the velocity scale factor, a near-time-optimal trajectory can be obtained. Simulation results along with inverse control of path-following are given to validate the generated trajectory
Near minimum-time direct voltage control algorithms for wheeled mobile robots with current and voltage constraints
No full textNear minimum-time direct voltage control (DVC) algorithms synthesizing path-planning and path-following are proposed for wheeled mobile robots (WMRs) satisfying (i) initial and final postures and velocities as well as (ii) voltage and current constraints. To overcome nonholonomic and nonlinear properties of WMRs, we divide our control algorithm for cornering motion into three sections: TSD (Translational Section of Deceleration), RS (Rotational Section), and TSA (Translational Section of Acceleration). We developed off-line DVC algorithms using the quadratic problem with the object function minimizing the total time, where voltages to the motors are controlled directly without velocity/torque-servo modules. while satisfying the current constraints. Two methods of searching for the two control parameters (number of steps for RS M(R) and velocity constraint in RS beta) were considered: The one is composed of one simple 1-dimensional search for beta, and the other is composed of two 1-dimensional searches for M(R) and beta which has better performance. Performances of the proposed control algorithms are validated via various simulations
Comparative economic analysis between direct and indirect wiring in the copper-based local loop
No full textIn a copper-based local loop, a circuit pair is indirectly connected to each subscriber usually via a primary cross connection point (PCP) which acts as a buffer to absorb circuit demand fluctuations among subareas. But some telephone operators adhere to the classic practice of direct wiring based on technological preferences without taking advantage of cost-efficient flexibility points. We analyse the extra cost of maintaining the old: practice of direct wiring over the popular one using flexibility points in a single PCP area. For that, the expectation of circuit shortages in subareas during a single replenishment period for the direct wiring is first obtained. Exploiting the convexity of the expectation, we then present a procedure for optimally allocating circuits among subareas, which not only sen es its own purpose of circuit provisioning for the direct wiring but also precisely calculates the extra cost over the indirect case
The control of cell adhesion and detachment on thin films of thermoresponsive poly[(N-isopropylacrylamide)-r-((3-(methacryloylamino)propyl)-dimethyl(3-sulfopropyl)ammonium hydroxide)]
No full textThis paper describes the formation of poly(N-isopropylacrylamide) (PNIPAAm) and poly[(N-isopropylacrylamide)-r-((3-(methacryloylamino)propyl)-dimethyl(3-sulfopropyl)ammonium hydroxide)] (P(NIPAAm-r-MPDSAH)) films on a glass surface via surface-initiated, atom transfer radical polymerization as a cell-culture platform. The films of PNIPAAm with various thicknesses and of P(NIPAAm-r-MPDSAH) with various ratios of NIPAAm and MPDSAH are formed to investigate the behaviors of cell adhesion and detachment. In the case of the PNIPAAm-grafted glass surfaces, the optimal film thickness, achieving the effective control of both cell adhesion and detachment, is estimated to be 11-13 nm for NIH 3T3 fibroblast cells. The adhesion and detachment behaviors of NIH 3T3 fibroblast cells are further tuned by incorporating the hydrophilic and non-biofouling MPDSAH moiety into the PNIPAAm system. The cell adhesion and detachment are controlled best, when the ratio of NIPAAm and MPDSAH is 75:1 (NIPAAm:MPDSAH). (C) 2009 Elsevier Ltd. All rights reserved
RDF version of the data from Choi, JS. et al. Towards a generalized toxicity prediction model for oxide nanomaterials using integrated data from different sources (2018)
No full textThis is an RDFied version of the dataset published in Choi, JS., Ha, M.K., Trinh, T.X. et al. Towards a generalized toxicity prediction model for oxide nanomaterials using integrated data from different sources. Sci Rep 8, 6110 (2018)
The original dataset publication DOI: https://doi.org/10.1038/s41598-018-24483-z
The Original publication authors: Jang-Sik Choi, My Kieu Ha, Tung Xuan Trinh, Tae Hyun Yoon & Hyung-Gi Byu
A Statistical Method to Generate Various Foreign Word Transliterations in Multilingual Information Retrieval System
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